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Working Fire Alarms Save Lives

December 4, 2018

Fire Alarm


Fire alarm systems are electronic devices used in commercial businesses and in some residences. These systems are designed to help minimize the number of lives lost to fire and smoke emergencies, and also to help protect property and buildings from fire damage. Fire alarms come in a variety of designs, and are installed based on the requirements of an individual building.


The need for fire alarm systems is determined by local building codes. In most residences and small commercial buildings, a system of smoke detectors is usually adequate for fire protection. For larger commercial structures, a fire alarm system is virtually always required, yet the design and scope of the system varies from region to region. During the project design phase, the project architect or mechanical engineer will review local building codes to determine compliance. If they determine that a fire alarm system is required, a system will be designed in agreement with the Standards of the National Fire Protection Association (NFPA). NFPA Standard 72 covers fire alarm design and installation in the US, and has been adjusted with only minimal alterations by most municipal governments.


A fire alarm system consists of a number of different components. The core of the system is the control panel, which contains monitoring and control devices that affect all other alarm components. The panel is powered by a dedicated power supply, and then supported by a backup battery power source in case of emergency. The system is triggered when a manual alarm pull is used, or when smoke or heat detectors detect signs of a fire. On activation, a system of alerts is put in motion to alert occupants of the fire. These may include strobe lights, horns, buzzers, or verbal evacuation signals.

Types of Systems

Fire alarm systems may also be manual or automatic. Manual systems are operated through the use of pull handles, which may be installed behind a sheet of protective glass to prevent tampering. Most manual systems can also be triggered manually by means of a switch or button on the panel. Automatic systems use technology to sense fire danger. They will often feature heat, smoke, or fire detectors placed on ceilings or walls. Certain detectors can even sense non-fire related emergencies, such as toxic gases or chemicals. NFPA 72 ordains how many of these detectors must be used, and where they should be placed.

Types of Alert Devices

By tradition, audio alerts were the customary type of notification device used with fire alarm systems. They featured a buzzing or ringing sound that alerted occupants to fire danger. When the American With Disabilities Act was established in 1990, fire alarm standards were changed to include both visual and audio notification. This was implemented to accommodate the nearly ten percent of Americans who are hearing impaired. Visual signals may include a red or white flashing light, and are ordinarily built into the same device as the audio speaker. Meanwhile, NFPA has discovered that typical audio alerts are becoming ineffectual. Instead of buzzers or bells, NFPA 72 now requires that voice evacuation systems are used. These devices are far more efficient for fast evacuations, and can clear a building much quicker by combining exit instructions with the conventional fire warnings.

Auxiliary Devices

When a fire alarm is triggered, the foremost response is an attempt to evacuate the building. Contingent on the location of fire, though, this is not always possible. To help protect lives and property, auxiliary devices are automatically set into action as fire alarm alerts are taking place. Initially, any smoke or fire doors that are being held open by magnetic holds are electronically released. This prompts the doors to automatically close and latch, preventing the spread of smoke or fire past these openings. After that, the alarm system motions air duct controls to the presence of smoke. When this transpires, duct dampers will shut and fans will cease operation, helping to stop the spread of smoke to occupied spaces.

Fire Alarm Inspection

Fire Alarm Systems are required by law to have a yearly inspection and testing performed (NFPA 72).

For further information, or to schedule an inspection or consultation, please contact McCurdy Electrical Services. Ph. 781-595-7074 | Em. info@mccurdyelectric.com | www.mccurdyelectric.com


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